With many battling the torrential wind and rain to make it to their desks on time for the new-year return to work, it’s not just the weather and post-Christmas blues that are the problem. Leaving early in the morning when it’s dark, working in an office that has little natural light – and then returning home when it’s dark – is putting workers’ mental health at risk, says MHRUK.

Its survey of 2,000 people showed that 30% leave home in the morning before sunrise and return post-sunset in the evening. If their workplace is also dark, then this can put them at risk of winter depression, or seasonal affective disorder (SAD). One in 10 work all day with insufficient light –and half the people surveyed were concerned that their workplace did not have enough natural light.

MHRUK says it is estimated that a million working hours are lost each hour due to SAD. “The common unhealthy work culture where lunch breaks are frowned upon is a likely contributor to the increasing numbers of SAD sufferers,” says Dr Laura Davidson, mental health barrister and trustee of MHRUK.

The charity is calling on employers to bring more light into the workplace – offering decent lighting in darker areas if natural light is impossible. It is also attempting to counteract the gloom with its Blooming Monday campaign, encouraging workers to ditch the greys and embrace vibrant colours from their wardrobes. Monday 20 January is deemed the gloomiest day of the year – hence giving an excuse to defy the dark and wear more colourful, cheerful clothes to lift the mood.

SAD can affect your energy, appetite and mood. As well as putting yourself in light-filled environments as much as possible, the NHS advises that SAD can be treated with therapy and anti-depressants, where appropriate.